Good flick! Carpenter is in top form.
The film is essentially Shutter Island with chicks. The monster/killer is very reminiscent of Prince of Darkness. In fact, this movie shares a lot in common with Prince of Darkness especially the very last shot of the film (which I won't spoil, but it's a classic Carpenter ending)
The film also contains another Carpenter staple - strangers thrown into a situation together and having to work together, despite their differences, to survive.
There were some jump out of your seat scares - lots of quiet moments interrupted by loud musical stingers - which made a few people scream. Harris' son is essentially the Ben Kingsly doctor character who is trying to get through to the main character and "cure" her.
Carpenter did not do the music unfortunately, some new guy, I forget his name, but the score was Carpenter-esque and very effective. Lots of wordless female "ooohing and ahhhing" if you know what I mean. Kind of Hitchock-ish main titles sequence.
Some great death scenes (one that reminded me of Halloween 2) and gore. Carpenter's still got it. I really hope he gets more work after this.